The present invention relates to a process for the preparation of chloro-benzoylchlorides from a chloro-trichloromethylbenzene in which said chloro-trichloromethylbenzene is treated with water in the presence of a Lewis acid at temperatures below 80.degree. C.
Chloro-trichloromethylbenzene compounds are suitable intermediates for the preparation of a broad variety of compounds which are useful as agrochemicals, pharmaceuticals or liquid crystals. In particular, they are key intermediates in the preparation of fungicidal dimethomorph (e.g. EP 0 120 321) and fungicidal benzophenones which are described for example in EP 0 727 141 A.
The German patent no. 331696 (Jul. 17, 1914) discloses a process wherein trichloromethylbenzene is treated with equimolar amounts of water in the presence of FeCl.sub.3 at elevated temperatures to form benzoylchloride.
However, this process is hardly applicable in technical scale since it causes problems with respect to the dosing rate and the exact equimolar dosing of water at elevated temperatures. Any excess of water will cause hydrolysis of the desired acid chloride compound and therefore reduce the yields.